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Transmission of life-threatening bacterial infections can occur when health-care personnel do not adhere to Standard Precautions and instead use medication in containers labeled as single-dose or single-use for more than one patient (1). This report summarizes the investigation of two outbreaks of invasive Staphylococcus aureus infection confirmed in 10 patients being treated for pain in outpatient clinics. In each outbreak, the use of single-dose or single-use vials (SDVs) for more than one patient was associated with infection transmission. In both investigations, clinicians reported difficulty obtaining the medication type or vial size that best fit their procedural needs. These outbreaks are a reminder of the serious consequences that can result when SDVs are used for more than one patient. Clinician adherence to safe injection practices, particularly when appropriately sized SDVs are unavailable, is important to prevent infection transmission. If SDVs must be used for more than one patient, full adherence to U.S. Pharmacopeia standards is critical to minimize the risks of multipatient use.

Pain Management Clinic — Arizona

On April 8, 2012, the Arizona Department of Health Services was notified of a patient with acute mediastinitis with blood and pleural fluid cultures positive for methicillin-resistant Staphylococcus aureus (MRSA). The report indicated this patient and two other patients with culture-confirmed invasive MRSA infections had undergone procedures recently at an outpatient pain management clinic.

Investigations by the county and state health departments confirmed that the three MRSA-infected patients received pain injections on the same day, along with 25 other patients. Two MRSA-infected patients received epidural steroid injections, and one received a stellate ganglion block. Ten persons, including the MRSA-infected patients, received contrast injections for radiologic imaging to guide medication needle placement. Each morning, clinic staff members typically prepared contrast medium in the patient procedure room, before the arrival of patients; two new syringes were used to withdraw 5 mL each from a 10 mL SDV of contrast medium (300 mgl/mL) and a 10 mL SDV of saline solution. The contents from each syringe then were transferred to the alternate vial, resulting in two 10 mL vials of diluted contrast solution, one for use in the morning and one reserved for the afternoon. Among patients receiving contrast on the day of the outbreak, six received injections from the morning vial and four from the afternoon vial. All of the patients with MRSA infections received diluted contrast from the afternoon vial.

The three patients with MRSA infections went to a local hospital 4–8 days after their outpatient pain remediation procedures. They required inpatient care for severe infections, including acute mediastinitis, bacterial meningitis, epidural abscess, and sepsis. Hospitalization ranged from 9 to 41 days, with additional long-term acute care required for one patient. The fourth recipient of diluted contrast from the afternoon vial was found deceased at home, 6 days after treatment at the clinic. The cause of death was reported as multiple-drug overdose; however, invasive MRSA infection could not be ruled out.

Samples from six unopened vials of contrast medium from the lot in use by the facility at the time of the outbreak were sent to CDC for analysis. No intrinsic contamination was identified using standard bacterial culture methods. Unopened vials of saline were not cultured because the lot in use at the time of the outbreak was not available and saline was routinely used as part of other procedures at the clinic that were not associated with infection. The Food and Drug Administration was contacted for additional reports of intrinsic contamination associated with the contrast medium; none had been reported.

In addition to identifying improper reuse of SDVs for more than one patient, county health officials also noted that health-care personnel did not adhere to Standard Precautions because they failed to wear face masks when performing spinal injections (2). In response to this outbreak, the Arizona Department of Health Services provided recommendations to the facility regarding Standard Precautions, including safe injection practices, and CDC's Guide to Infection Prevention for Outpatient Settings: Minimum Expectations for Safe Care (3).

Orthopedic Clinic — Delaware

The Division of Public Health of the Delaware Department of Health and Social Services was notified on March 19 of seven patients admitted to a hospital with evidence of septic arthritis or bursitis. Cultures of fluids from the affected sites (knee [three patients], hip [two], ankle [one], and thumb [one]) indicated that all of the patients had methicillin-susceptible S. aureus infections. All seven patients required debridement of the infected sites and intravenous antimicrobial therapy, with an average length of hospitalization of 6 days (range: 3–8 days). All seven patients had received joint injections from the same outpatient clinic during March 6–8.

Site visits to this hospital-affiliated orthopedic clinic were conducted by personnel from hospital infection prevention and risk management departments. Thirteen patients had received joint injections for pain remediation during the 3-day period. Of the seven patients with S. aureus infections, five received their injections on the same day. Three additional patients who received injections during March 6–8 developed symptoms that suggested an infection but did not have cultures taken and were treated with oral antibiotics on an outpatient basis.

The reuse of SDVs of the anesthetic bupivacaine for multiple patients was the only breach of safe practice identified during the investigation and represented a recent change. Previously, the orthopedic practice had used 10 mL SDVs of bupivacaine for single-patient use. When a national drug shortage disrupted the supply of 10 mL SDVs, office staff members began using 30 mL SDVs of bupivacaine for multiple patients. The joint injection procedures typically required 1–8 mL of anesthetic, with each injection prepared immediately in advance of the procedure in a separate, clean, medication preparation room. Only one 30 mL vial of bupivacaine was opened at any given time; each vial was accessed over a course of several hours for multiple patients until all contents were withdrawn. Occasionally, an opened 30 mL vial was stored in a medical cabinet for use the next day.

Six S. aureus isolates from clinical cultures were tested by CDC, found indistinguishable by pulsed-field gel electrophoresis (PFGE), and identified as PFGE type USA600. As part of the investigation, nasal swabs were collected from the three clinic medical providers and four ancillary staff members who were involved with the preparation or administration of injections. Two staff members whose responsibilities included preparing injections were colonized with S. aureus; one had a strain that was indistinguishable from the outbreak strain.

In response to this outbreak, health-care providers and ancillary staff members received extensive education regarding Standard Precautions, including safe injection practices. The Division of Public Health also issued a statewide health alert to the medical community regarding injection safety (4).

Editorial Note

The outbreaks described in this report demonstrate the serious consequences that can result from misuse of SDVs. Medications labeled as "single dose" or "single use" typically are preservative-free and should be dedicated for single-patient use to protect patients from infection risks (5). In both outbreaks, health-care providers reported difficulty in obtaining specific medication types and vial sizes, prompting them to use contents from SDVs for more than one patient. As evidenced by these outbreaks, the smallest vial size manufactured can exceed the amount routinely needed for individual patients. Furthermore, although contrast medium is manufactured in lower concentrations, such that dilution can be avoided, the Arizona clinic reported difficulty obtaining a reliable supply of the lower concentration.

Proper use of SDVs in clinical settings consists of 1) withdrawing contents into a new sterile syringe in an aseptic manner, 2) promptly using the contents for a single patient during a single procedure, and 3) disposing of the vial and any remaining contents. To prevent unsafe practices and patient harm, CDC recently issued a communication clarifying recommended practices for safe use of SDVs (1). The safest option remains dedicating SDVs to individual patients. When individually packaged and appropriately sized SDVs are unavailable, qualified health-care personnel may repackage medication from a previously unopened SDV into multiple single-use vehicles (e.g., vials or syringes). However, this procedure should only be performed using a laminar-flow hood in accordance with standards in U.S. Pharmacopeia General Chapter 797 (Pharmaceutical Compounding — Sterile Preparations). Strict adherence to U.S. Pharmacopeia 797 standards is critical and might have helped prevent recent outbreaks associated with unsafe practices (6,7). These outbreaks could be avoided if smaller medication vial sizes that better fit procedural needs were manufactured.

Since 2007, the year that injection safety was included as part of Standard Precautions, 20 outbreaks associated with use of single-dose or single-use medications for more than one patient have been reported (1; CDC, unpublished data, 2012). These investigations help remind health-care providers of infection prevention practices that are critical for patient safety. These outbreaks also demonstrate the critical role of public health experts in investigating clusters of health-care–associated infections. Whereas the Delaware facility received infection prevention assistance from an affiliated hospital, the Arizona facility did not have access to a similar resource, apart from the guidance provided by the state and county health departments. When outbreaks or clusters are identified, prompt notification of public health authorities is imperative to ensure that appropriate case-finding activities and infection control measures are implemented to prevent additional harm.

Transmission of life-threatening infections can occur when single-dose or single-use vials (SDVs) are used improperly for multiple patients. In 2007, CDC included injection safety as part of Standard Precautions.

What is added by this report?

In 2012, a total of 10 patients in Arizona and Delaware were confirmed to have invasive Staphylococcus aureus infections following pain injections at two outpatient clinics. These Infections were associated with multipatient use of SDVs. Difficulties in obtaining appropriate vial sizes, either because of a national drug shortage or because the vial size needed by health-care providers was not manufactured, might have led to deviation from recommended practices. Since 2007, the year that injection safety was included as part of Standard Precautions, at least 20 outbreaks associated with use of single-dose or single-use medications for more than one patient have occurred.

What are the implications for public health practice?

Public health authorities play a critical role in investigating outbreaks in health-care settings and helping to implement control measures. In addition, practices identified as part of these investigations help in the development of evidence-based infection prevention recommendations. This report reminds health-care providers of the serious consequences of multipatient use of SDVs that can occur even when health-care workers believe they are being careful.

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